In the past, a method of generating a polarized image using an imaging unit and a polarizer has been disclosed. For example, Patent Document 1 discloses a method in which a polarizer is disposed in front of an imaging unit to generate a polarized image with a plurality of polarization directions by photographing while this polarizer is rotated. Meanwhile, there is disclosed a method of generating a polarized image with a plurality of polarization directions different from each other by imaging at one time using polarizers with different polarization directions provided for respective pixels.
Additionally, normal line information on an object is generated from a polarized image with a plurality of polarization directions. For example, in Non-patent Document 1 and Non-patent Document 2, normal line information is generated by applying a polarized image with a plurality of polarization directions to a model formula.